+31 15 factorial is 1307674368000 (thx Google) under base 10. When converted to base 12, it turns into 191529600000.
There are 5 zeroes.
+118687 15! = 1307674368000 base 10 but you do not need to know this
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I can work out that there will be 3 zeros in base 10 quite easily. All I need to know is how many factors of 10 are there.
10=2*5 so I am going to pull out all the 2 and 5 factors.
1*2*3*4*5*6*7*8*9*10*11*12*13*14*15
2 22 5 2 222 25 22 2 5 = 2^12 * 5^3 = 10^3 *2^9
so 15! can be divided by 10 three times so there will be 3 zeros in base 10
Which is what the calc gave me in the first place.
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To find how many zeros there will be base 9 then you have to work out how many factors of 9 go into it.
9=3*3
So see how may threes go into it and half that number will be your answer for trailing zeros base 9
